• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

F-100 Super Sabre 1/8th Build (70")

thenated0g

Drinker of coffee, Maker of things
Mentor
#1
So a few years ago i watched David's hot wire cutting video on the Viggen, but never considered that it would be possible to do something similar myself. Fast forward and i have now hot cut a few things myself and gained some confidence. As i was looking for a new project i came across the 3 view above and noticed that the main wing of the F-100 looked almost identical to a fpv flying wing with center section. Knowing that i could make a flying wing fly and that this was the main lift of this jet, i decided to give it a go.
1934806990541310078_account_id=1.jpg 2274630150185371228_account_id=1.jpg


Not wanting to start from scratch i searched thru online plan databases and found this free plan for a balsa build. I Modified it slightly in Inkscape. Upscaling it to around 69" nose to tail and modifying the wing so it has less sweep, deeper wingtips and slightly increased wingspan over scale. I rounded it up and got the wingspan around 70". The idea was to give it more wing area and more stable slow flight. Combined with a modified clark Y airfoil i am hoping that it will have have much nicer slow flying. Did i mention no landing gear? Yeah....Slow flying needed for launch.
plans 1.JPG plans 2.JPG


I ordered full size plans from Staples online. I cut out the "firewalls", glued them to doorskin plywood, and cut out the templates using a scroll saw. On the plans i marked out the distance of foam i will need in between each firewall and the distance off the table the templates need to be as it tapers up to the nose and tail. As this will be a pusher and not edf the inside of the plane didn't matter, but i did add a tunnel for access to parts, routing of wires, and airflow.
IMG_20170815_195144.jpg IMG_20170816_212829.jpg IMG_20170828_202620.jpg IMG_20170926_175908.jpg


The foam i am using is from Home Depot. It is 2" thick 4x8 solid insulation. Although i do have some factory edge pieces most of the foam i had was scraps from other planes so a lot of time was spent getting a nice straight edge, cutting pieces into squares and gluing together. Lots and Lots of layers and gorrilla glue. 69" divided by 2" plus a few 1" pieces here and there...so boring.
IMG_20170821_201519.jpg IMG_20170821_201920.jpg 8602476338380763285_account_id=1.jpg IMG_20170822_185507.jpg IMG_20170825_191545.jpg IMG_20170828_202554.jpg


After the pieces were glued together i would adjust if needed. For instance if a section needed to be 5.5" i would cut 1/2 an inch off. I would than mark the center all around and if needed how far up the template needed to be off the table. After a section would be cut i would than glue multiple sections together as in the 4th pic below.
IMG_20170829_080312.jpg IMG_20170829_080752.jpg IMG_20170926_175754.jpg IMG_20170927_213622.jpg

to be continued.......
 

thenated0g

Drinker of coffee, Maker of things
Mentor
#2
The nose is pretty unique. I probably should have started on a middle section when cutting. I made a few mistakes as the wire i am using started cutting into the wood templates and creating large holes in the foam. Not too big of a deal and this entire process is me learning what to do. I really have no idea what i am doing lol. This foam is very easy to fill and sand so shouldnt be much work later. Pretty cool to see it taking shape though.
IMG_20170825_215229.jpg IMG_20170827_202016.jpg IMG_20170903_083507.jpg IMG_20170904_083259.jpg


The wings are no different than a fpv flying wing to cut out. The clark Y airfoil is very popular as it allows a model builder to build the wing easily while keeping it flat as the bottom IS flat. This is why its used in foam board builds. When it comes to hot cutting the benefit is that you only need to cut the top and leading edge of the wing core. The bottom is already flat. Just a little sanding required at the transition from hotting to factory foam. Like one swipe of sand paper. On these big builds i find it significantly less frustrating and accurate to just mark the dimensions out with a ruler instead of taping a bunch of paper together and cutting out.
IMG_20170902_152226.jpg IMG_20170902_174142.jpg IMG_20170903_143109.jpg IMG_20170903_142858.jpg


I thought about this stage of the build for a long time. Cut out the wings hole ahead of time? Dont use a hole and attach them to the fuselage? In the end i decided that the strength of the main wing is most important and that i needed to build it as one piece with spars and covering. Plus too waiting to cut the whole in the fuselage meant that the fuselage was much stronger while working with it up to this point. After doing this and looking at the result and contemplating trying to transport this thing...basically its like a 70" square...where the heck is that going to fit ?!? I decided to remove the fuselage piece under the wing and make the entire wing section removable using some wood and plastic bolts. Still working on that part of the build.
IMG_20170930_110443.jpg IMG_20170930_110451.jpg IMG_20170930_123513.jpg IMG_20170930_123522.jpg IMG_20170930_123536.jpg
 

thenated0g

Drinker of coffee, Maker of things
Mentor
#5
The tail section was the final glued up section. I needed a motor mount and decided just to glue the template that was on the back and already the perfect size. I added some extra holes for airflow. The motor is a Emax GT 4020/470kv motor. That is a 16x10 prop in the picture. Combined with a 6s battery this puts out around 5,100g of thrust. This is one of the two motors i was running on my 120" 39lb 200% FT guinea pig. I also cut out the spot where the esc will be located flush mounted under the fuselage for airflow.

IMG_20170927_214006.jpg IMG_20170929_073101.jpg IMG_20170929_073156.jpg IMG_20170929_073217.jpg IMG_20170930_130633.jpg


As i mentioned earlier i had cut some big lines down the nose. Since it would require a lot of spackle to fill and spackle isn't very strong i decided to fill the majority with gorilla glue. Pretty easy process of just adding glue and water and taping over the top. It expands to fill the area pretty well. Anything else will be filled with spackle.
IMG_20170930_181852.jpg IMG_20170930_181856.jpg IMG_20170930_182145.jpg
 

thenated0g

Drinker of coffee, Maker of things
Mentor
#6
One thing i haven't gone over yet is how i plan on covering the foam. I had seen some old videos on using watered down glue and paper, kind of like Peter's waterproofing covering. I have made a playlist of some how to videos below. Testing this process is actually what has the build on pause. I am trying out a couple different ways of doing it. So far i am really impressed with the strength of the finished covering.

https://www.youtube.com/watch?v=xcLrUQ1nGHU&list=PLMieSP4Ym7qpl-Fi0Y4__t7E5QOKhwcjU
 

thenated0g

Drinker of coffee, Maker of things
Mentor
#7
IMG_20170930_142033.jpg IMG_20170930_182202.jpg

Pretty exciting getting it to this point of the build. It is taller than me now. Weight of the fuselage at this point is 1kg. I still need to figure out where the battery is going to be and cut a hatch. I going going to aim for as far forward as i can and still keep the nose strong. The motor is 298g way in the back but i have just as much distance/leverage in front of cg for the battery and it will be a minimum of 500g (6s !!!). I have to figure out exactly where the different parts are going, no "how to" builds on this guy. Thats what takes so long on these big builds, just thinking about everything over and over and imagining parts and things inside.

The tail is going to be a fully moving elevator. I have some carbon tubes that fit inside of each other so i will have the elevators connected thru a tunnel of carbon and move together, not separate as the scale plane does.

So far in my plans the vertical stabilizer is going to not have a rudder and will friction fit and be removable.

All tail feathers will be single sheet thickness of coroplast with some kite rods glued in the flutes to keep them rigid.

Lots of sanding ahead of me on this fuselage and than lots of filling and more sanding.

Still have to cut out the center section of the main wing and build that, which wont take long.

ohh yeah landing gear. I hate landing gear so much. Guys at my local club were actually making fun of all my belly landers so i am actually taking it as a challenge to not have landing gear on this thing. My current plan is to create a takeoff "cart". More on that later.
 

thenated0g

Drinker of coffee, Maker of things
Mentor
#9
IMG_20171021_215303.jpg IMG_20171022_211144.jpg IMG_20171023_075921.jpg

Cut out the center section. 9" wide and 22" deep. Glued together with low temp hot glue. Than i cut in paths for the glass fiber kite rods with my heated soldering iron. They are pretty small but very strong once glued in place. Again with low temp glue. Top and bottom. CG is 11" back from leading edge. I marked this as right above this spot in the fuselage i want a spot for an extra battery. In the future if i want to get longer fpv flights i will be able to put a second battery in at cg and not have to worry about shifting cg, the plane will just be heavier.

As such my servo wires from the ailerons need to come up somewhere NOT in this location to keep things clean.

I have some 2" aileron balsa stock so i cut out 2" off the trailing edge. I want non scale full length ailerons so i can use them as flaps and have a LOT of flaps drop if i need it. See flaperons

Weight fully sparred up right now is 470 grams.
71 in wingspan. 22" root chord.
 
#10
Dude, I think we just became best friends. I will be following this with much enthusiasm and vicariousness (not sure thats a word). I can literally NOT WAIT for more updates. Sub'd
 

thenated0g

Drinker of coffee, Maker of things
Mentor
#11
LOL thanks man. I would describe myself as a builder who occasionally flies. My hobby is more the little bit of time i get to spend every night working on projects more than i would say the end product, so if you want more timely updates i suggest following my IG account as that is the least amount of work to post and so i use it regularly and than just dump to youtube or here when i get a certain amount of stuff to post. https://www.instagram.com/thenated0g/

Im going for something that is mainly for FPV so function over scale. I wanted something that is fpv, but more interesting to look at than all the standard flying wings and something from a design/build standpoint that is different than what i am used to. I think the main thread thru all my builds is always doing something or using some technique that i have never done to keep me learning and excited about it.
 

Geeto67

Posting Elsewhere
#15
Based on size and general project objectives, have you put any thought into using the foam to make a fiberglass mold and then building the plane out of fiberglass or carbon fiber?

Big rc planes have been made out of glass for ages, it adds strength, makes it easier to paint, hollows out the insides to allow easy mounting of all sorts of equipment, and depending on the weight of the foam maybe makes it lighter too.
 

thenated0g

Drinker of coffee, Maker of things
Mentor
#17
Based on size and general project objectives, have you put any thought into using the foam to make a fiberglass mold and then building the plane out of fiberglass or carbon fiber?

Big rc planes have been made out of glass for ages, it adds strength, makes it easier to paint, hollows out the insides to allow easy mounting of all sorts of equipment, and depending on the weight of the foam maybe makes it lighter too.
Yes and i may try that in the future. I really really hate the smell of epoxy though and i have a 5 year old daughter. And the mess from epoxy too...

One of the reasons i went this route over epoxy and bagging is that you just cant find many full tutorials at all on the subject and the ones i can find skip over a ton of things that the builders just assume is common knowledge. I have discussed this with guys at the club before that there is a real disconnect in knowledge between the older flyers and us guys coming into the hobby via foamboard. A lot of these old processes we didnt even know exist and when learning by yourself you are limited to what is available or easily searchable online.
 

Geeto67

Posting Elsewhere
#18
Yes and i may try that in the future. I really really hate the smell of epoxy though and i have a 5 year old daughter. And the mess from epoxy too...
For me its the itchiness that comes after sanding. I have a 5 year old daughter too and I solve this smell problem by working in the garage and not letting her in there. Mess can be managed, in my teens I worked in a shop that restored corvettes and I learned from the master fiberglass guys there that although fiberglass can sometimes be messy with the sanding and mat and chop handling, you don't have to work messy. Those guys worked so clean it was amazing and their stuff rarely contaminated.


One of the reasons i went this route over epoxy and bagging is that you just cant find many full tutorials at all on the subject and the ones i can find skip over a ton of things that the builders just assume is common knowledge. I have discussed this with guys at the club before that there is a real disconnect in knowledge between the older flyers and us guys coming into the hobby via foamboard. A lot of these old processes we didnt even know exist and when learning by yourself you are limited to what is available or easily searchable online.
I have this same issue, and agree with you 100%, except to say don't limit yourself to what is "easily searchable" online. Sometimes you have to think outside the box and get out there and talk to people. I learned to work with epoxy from those corvette guys, surfers, boat guys, and stage set and prop builders - very little from videos online. Sometimes you just have to be social and can't hide in the workshop. The internet is good for getting your confidence up but it is by no means a comprehensive instruction manual.

I can tell you that I learned RC starting in a pre-internet time by starting with something that was complete and working backwards slowly until I could do stuff from scratch. I started with ARF kit airplanes, moved to ARC (Almost ready to cover), then kits, then I scratch built one and stopped (because college, girls, hot rods, motorcycles, guitars, and flying lessons). I learned motorcycles the same way: bought a running bike, learned to maintain it, then bought an "easy" project, then did a restoration. It's about leaning into your comfort zone and learning from the setbacks. I failed many times (my first fiberglass motorcycle tank disintegrated the first time I put fuel in it). Sometimes you just have to take baby steps and do it and keep doing it.

I The knowledge isn't "hiding", our predecessors had to "discover" some build techniques and they are still out there to be discovered - you just kind of have to immerse yourself. Foamboard has it's limitations, at some point you just have to bite the bullet and build a balsa or fiberglass kit just to learn new skills.
 
Last edited:

thenated0g

Drinker of coffee, Maker of things
Mentor
#19
I totally agree. I love learning things on my own. But in this case i meant trying to research how others had done something before doing it my way. If i can i would rather someone else make the mistakes first :)
 

Geeto67

Posting Elsewhere
#20
I totally agree. I love learning things on my own. But in this case i meant trying to research how others had done something before doing it my way. If i can i would rather someone else make the mistakes first :)
I totally get that. But sometimes the absence of knowledge is just because the hobby moved the other way and what you are doing isn't ideal.

Here is a good example: You mentioned covering the foam before, and a paste and tissue method (similar to paper mache' by the way). Well a lot of this is similar to old tissue (or silk) and dope methods for covering wood airplanes. People don't really use tissue and dope anymore because monokote and other plastic lightweight coverings came out and made them obsolete. Now if you want to know how to tissue and dope an airplane, you have to run in the indoor free flight circles and even some of those guys skip the dope process for weight. The hobby will always move to the simple solution.

You don't see a lot of foam airplanes built like the way you are doing it because once fiberglass was available it was the same process as covering the foam to make a mold that you could then use to make fuselage after fuselage. There has been a resurgence of foam construction planes recently because it really wasn't explored way back when - once die cutting balsa and creating molded foam shapes became cheap enough manufacturing techniques - there wasn't a rsuh for people to scratch build from foam.

In terms of covering I am going to say use the balsa wood dope and tissue technique. Take a mix of white glue and water (between 50/50 and 65/35) with food dye in it (just so you can see what areas you have worked) and brush it on. First coat protects the foam. Second coat gives a sticky surface to lay the tissue down on. third coat covers the tissue over the top. fourth coat gives you a sand-able finish you can then paint once dry and sanded. Once you are done with all the work you'll understand why guys went to fiberglass, esp since at the time everything was nitro powered.

keep up the good work - you'll get there.